Spectroscopic study of sol-gel SiO2-SnO2 glass-ceramics with controlled nanocrystal size

Javier Del Castillo 1Carlos Yanes 1Jorge Méndez-Ramos 2Vicente Rodríguez 2

1. Dep Física Básica Universidad La Laguna, Av Astrofísico Fco Sánchez s/n, La Laguna 38206, Spain
2. DepFísicaFund.yExp.,ElectrónicaySistemas, Av Astrofísico Fco Sánchez s/n, La Laguna 38206, Spain

Abstract

In the past few years, nanostructured materials have focused much attention due to their potential technological applications. In particular when doped with RE-ions they are attractive for photonic applications [1]. With appropriate choice of host matrix and RE doping optical properties can be enhanced notably. In this respect, properties of semiconductor nanoparticles are interesting when their sizes are comparable or below the exciton Bohr radius. Tin oxide is a versatile n-type semiconductor with a wide band gap of 3.6 eV at 300K. Materials based on tin oxide have a wide range of applications like gas sensors or transparent conducting electrodes [2]. Tin oxide nanocrystals should have better optical properties than the bulk ones owing to quantum confinement.

In this work nanostructured samples based on SiO2-SnO2 have been obtained by a thermal treatment of sol-gel precursor glasses. Structural analysis has been performed by means of X-ray diffraction. The average size of the obtained nanocrystals can be predetermined using well controlled concentration of tin precursor. The mean radius of the nanocrystals is comparable to the exciton Bohr radius in an insulator SiO2 glass. Optical absorption and photoluminescence spectra have been measured as a function of tin oxide concentration. The nanocrystal sizes have been estimated as function of process parameters using the Brus and Scherrer equations. The band gap increase is in conformity with the theorical result based on the effective mass model. A mechanism has been proposed to explain the observed photoluminescence properties.

[1] G. Blasse, B.C. Grabmaier, Luminescent Materials, Springer, Berlin (1994).

[2] L. A. Kurihara, S.T. Fujiwara, R.V.S. Alfaya, Y. Gushikem, and S.C. de Castro J. Colloid and Interf. Sci 274, 2 (2004)

Acknowledgements: J. del-Castillo thanks "Universidad de La Laguna Beca SEGAI" for financial support.

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium C, by Javier Del Castillo
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-16 09:35
Revised:   2009-06-07 00:44
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